Things You Need To Know About Antihistamines

Antihistamines, more commonly known as antiallergic medications, are those needed to treat allergies. The common symptoms of allergy are runny nose, sneezing, cough, and watery eyes. Some antihistamines are given in other conditions too, such as:

  • Parkinson’s disease
  • Cough
  • Anxiety
  • Vomiting
  • Dizziness
  • Sleep problems

Antihistamines work by blocking the action of histamine- an inflammatory mediator that helps reduce allergy and inflammation.

If you have a complaint of allergy, you must attend follow-up visits with your healthcare provider. To get an expert opinion, you can consult a Pulmonologist in Lahore.

In What Forms Are Antihistamines Available?

Antihistamines are available in various forms such as capsules, liquids, tablets, drops, syrup, injections, and nasal sprays. Your healthcare provider will prescribe the form most compatible according to your condition and age.

Do I Need A Prescription To Buy Antihistamines?

Antihistamines are available over the counter. You do not need to have a prescription to buy them.

What Is Histamine?

Histamine is a chemical mediator that causes inflammation. It regulates various other chemical processes such as dilating blood vessels, stimulates gastric acid secretion, contraction of smooth muscle in the lungs, uterus, and stomach, and affects heart rate.

If your body encounters any foreign object, it causes an allergy in which histamine is released. It causes dilation of blood vessels and lowers blood pressure, which can become life-threatening, leading to shock.

How Are Antihistamines Classified?

Antihistamines are mainly of two types, classified as H-1 receptor blockers and H-2 receptor blockers.

The H-1 receptor blockers are used to lower the symptoms of allergy and H-2 receptor blockers to treat gastrointestinal symptoms such as gastroesophageal reflux disease, gastritis, motion sickness, peptic ulcer disease, nausea, and vomiting.

The H-1 antihistamines are further classified into two types, first-generation and second generation.

What Are The Type of H-1 Antihistamines?

As the name shows, first-generation antihistamines are older ones, which got approved in the 1930s by the FDA. The second-generation antihistamines are newer ones that got approved by the FDA in the 1980s.

The first-generation antihistamines are sedating drugs, which means they cause sleepiness. They act on the brain and spinal cord and cross the blood-brain barrier, therefore, causing sedation.

The second-generation antihistamines are non-sedating drugs, meaning they do not cause sleepiness when given in standard doses. They do not cross the blood-brain barrier.

Second-generation antihistamines are more commonly prescribed compared to first-generation antihistamines because they do not cause sedation when given in standard doses.

What Are Some Examples of Antihistamines?

You may need to take antihistamines if you are allergic, and they are available over the counter, which means you do not need a doctor’s prescription for it.

The examples of some first-generation H-1 receptor blockers are:

  • Brompheniramine
  • Chlorpheniramine
  • Clemastine
  • Doxylamine
  • Hydroxyzine
  • Phenindamine
  • Cyproheptadine
  • Dexchlorpheniramine Dimenhydrinate
  • Diphenhydramine

A few examples of the second generation H-2 receptor blockers are:

  • Azelastine
  • Desloratadine
  • Fexofenadine
  • Loratadine
  • Cetirizine

These drugs do not cause sedation as such when given in standard doses, compared to first-generation antihistamines.

Your healthcare providers may also prescribe antihistamines for gastrointestinal health conditions. In that case, they will prescribe H-2 receptor blockers, such as:

  • Cimetidine
  • Ranitidine
  • Famotidine
  • Nizatidine

What Conditions Do Antihistamines Treat?

The H-1 antihistamines are used to treat conditions such as:

  • Allergic rhinitis/hay fever
  • Allergic conjunctivitis
  • Hypersensitivity to certain drugs
  • Insect bites and stings
  • Hives and other skin rashes
  • Colds
  • Food allergies

They are also used to treat:

  • Motion sickness
  • Insomnia
  • Anxiety

The H-2 antihistamines are used to treat conditions such as:

  • Heartburn
  • Zollinger-Ellison syndrome
  • Gastroesophageal reflux disease (GERD)
  • Duodenal and gastric ulcers

They are also used to treat conditions such as:

  • Anorexia
  • Headaches
  • Parkinson’s disease- to decrease stiffness and tremors
  • Some types of bone pain
  • Anaphylaxis
  • Vertigo

The Bottom Line

Antihistamines are most commonly used to treat allergies. They are available over the counter, so you do not need a prescription for them.

If you have an allergy, you can consult with a pulmonologist at Surgimed Hospital.

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